by index

Python list and metadata definition and use operation example, python example This document describes how to define and use Python lists and metadata groups. We will share this with you for your reference. The details are as follows: # Coding =

DivCacmodule.controller (' Cacscripteditctrl ', Cacscripteditctrl); Cacscripteditctrl. $inject= [' $uibModalInstance ', ' $scope ', ' $compile ', ' $scope ', ' cacscriptservice ', ' messageservice ', ' entity ']; functionCacscripteditctrl

oracle| Performance | optimization 36. Replace or with union (applicable to indexed columns) In general, replacing or in a WHERE clause with union would have a better effect. Using or for an indexed column causes a full table scan. Note that the

There was a script that ran for a long time without results, and the results were instantly optimized. The original statement is as follows:sql> explain plan for 2 select * 3 from Crm_dg.tb_ba_channelstaff A, 4 crm_dg.tb_ba_s Ubscription_hist B, 5

When a WHERE clause uses a function for a column, the Oracle optimizer cannot use the index in the query unless the simple technique is used to force the index. In general, you cannot establish a specific condition on a specified column if you do

We know that the execution plan generated by oracle for each statement is placed in the explain pool. For the first time, it is hard parsed to generate hash values. Compare the hash value when you execute this statement next time. We know that the

During work, we often observe the space release and Application Performance Improvement brought about by index reconstruction. Space release is easy to understand and measure, so index reconstruction will be applied During work, we often observe the

This article mainly discusses the following kinds of index access methods: 1. Indexing unique Scan (Index unique SCAN)2. Indexing range Scan (Index range SCAN)3. Index full Scan (SCAN)4. Indexing skip Scan (index skipping SCAN)5. Index fast full

The following applies to Oracle 10.2.0.5 and aboveOne query is slow, and the original SQL is as follows:1 Select 2A.*3 from(Select 4 Ssi.id,5 'Small_station_info'TB,6(SelectSbi.name7 fromScene_base_info SBI8

The first day of spring festival is also a headache. Geer sent me another SQL statement. He said that the SQL dB file sequential read is very high and it takes 120 seconds to run, I can help optimize the logic read by 1626677. The SQL statement is

Transferred from: Access to the data dictionary view of the database is usually relatively fast, because Oracle has made special optimization work, but sometimes, when several data dictionaries are associated, CBO is not so intelligent, and

DOM parsing will map the entire XML file into the tree structure in document, and when it comes to larger files, it takes up a lot of memory and looks very slow. Sax is the solution for this scenario, and the SAX parser parses from the beginning

The memory model of the JVM runtime data area consists of five parts:"1" Method area"2" heap"3" Java stack"4" PC register"5" Local method stackfor string s = "haha", it's virtual machine directive:0:LDC #16; String haha2:astore_13:returnFor the

A. List　Lists: Lists are combinations of elements that are arranged in a specific order. A list is the equivalent of a container that can store any Python data type, which is also known as an array in another language.I. Creating an arrayLi = ['

A. List　Lists: Lists are combinations of elements that are arranged in a specific order. A list is the equivalent of a container that can store any Python data type, which is also known as an array in another language.I. Creating an arrayLi = ['

Oracle SQL Performance 1. ORACLE optimizer:. RULE (based on Rules) B. COST (COST-based) c. CHOOSE (optional) sets the default optimizer. various declarations of the OPTIMIZER_MODE parameter in the ora file, such as RULE, COST, CHOOSE, ALL_ROWS,

"_ Sort_elimination_cost_ratio" [SQL] create table t1 as select * from dba_objects where object_id is not null; alter table t1 add constraint t1_pk primary key (object_id ); create index t1_ind on t1 (object_type); alter session set optimizer_mode =

Using Reverse indexes to Improve the Performance of order by desc using reverse indexes (index desc) can greatly improve the performance of SQL statements with order by desc clauses. I. Scenario 1. Table Name: test_t, with a field name: object_id2,

In pinwu performance optimization, Chapter 4.4.3 describes the two features of composite indexes: prefix and optionality. What is prefix? This book describes how to exclude skipscanindex (there are not many pre-index columns, such as gender). If the

The collection is an important part of the. NET FCL (Framework Class Library), and we always have to deal with the collection of C # code, and the FCL provides a rich and easy-to-use collection type, which provides great convenience for us to